/*
 * Copyright (c) 2014 Strong Group - 版权所有
 * 
 * This software is the confidential and proprietary information of
 * Strong Group. You shall not disclose such confidential information 
 * and shall use it only in accordance with the terms of the license 
 * agreement you entered into with www.cnstrong.cn.
 */
package com.zuorenke.encrypt;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import java.security.SecureRandom;

/**
 *
 * 描述:Des加密工具类
 *
 */
public final class Des {

	private static final String PASSWORD_CRYPT_KEY = "!@#$%^&*()_+~`=-";

	private final static String DES = "DES";
	
	/** 
	* 加密 
	* @param src 数据源 
	* @param key 密钥，长度必须是8的倍数 
	* @return  返回加密后的数据 
	*/
	public static byte[] encrypt(byte[] src, byte[] key) throws Exception {

		//DES算法要求有一个可信任的随机数源 

		SecureRandom sr = new SecureRandom();

		// 从原始密匙数据创建DESKeySpec对象 

		DESKeySpec dks = new DESKeySpec(key);

		// 创建一个密匙工厂，然后用它把DESKeySpec转换成 
		// 一个SecretKey对象 

		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);

		SecretKey securekey = keyFactory.generateSecret(dks);

		// Cipher对象实际完成加密操作 

		Cipher cipher = Cipher.getInstance(DES);

		// 用密匙初始化Cipher对象 

		cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);

		// 现在，获取数据并加密 

		// 正式执行加密操作 
		
		return cipher.doFinal(src);

	}

	/** 
	* 解密 
	* @param src 数据源 
	* @param key 密钥，长度必须是8的倍数 
	* @return   返回解密后的原始数据 
	*/
	public static byte[] decrypt(byte[] src, byte[] key) throws Exception {

		// DES算法要求有一个可信任的随机数源 

		SecureRandom sr = new SecureRandom();

		// 从原始密匙数据创建一个DESKeySpec对象 

		DESKeySpec dks = new DESKeySpec(key);

		// 创建一个密匙工厂，然后用它把DESKeySpec对象转换成 

		// 一个SecretKey对象 

		SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);

		SecretKey securekey = keyFactory.generateSecret(dks);

		// Cipher对象实际完成解密操作 

		Cipher cipher = Cipher.getInstance(DES);

		// 用密匙初始化Cipher对象 

		cipher.init(Cipher.DECRYPT_MODE, securekey, sr);

		// 现在，获取数据并解密 

		// 正式执行解密操作 

		return cipher.doFinal(src);
	}

	/** 
	 * 密码解密 
	 */
	public final static String decrypt(String data) {
		try {
			return new String(decrypt(hex2byte(data.getBytes()), PASSWORD_CRYPT_KEY.getBytes()));
		} catch (Exception e) {
		}
		return null;
	}

	/** 
	 * 密码加密 
	 */
	public final static String encrypt(String password) {
		try {
			return byte2hex(encrypt(password.getBytes(), PASSWORD_CRYPT_KEY.getBytes()));
		} catch (Exception e) {
		}
		return null;

	}

	/** 
	* 二进制转字符串 
	*/
	public static String byte2hex(byte[] b) {

		String hs = "";

		String stmp = "";

		for (int n = 0; n < b.length; n++) {

			stmp = (Integer.toHexString(b[n] & 0XFF));

			if (stmp.length() == 1)

				hs = hs + "0" + stmp;

			else

				hs = hs + stmp;

		}

		return hs.toUpperCase();

	}

	public static byte[] hex2byte(byte[] b) {

		if ((b.length % 2) != 0)
			throw new IllegalArgumentException("长度不是偶数");

		byte[] b2 = new byte[b.length / 2];

		for (int n = 0; n < b.length; n += 2) {

			String item = new String(b, n, 2);

			b2[n / 2] = (byte) Integer.parseInt(item, 16);

		}

		return b2;
	}
}